Arcing gap



DEGo 28, 1937. R g g 2,133365 ARCING GAP Filed July 27, 1935 2Sheets-Sheet l l @a i Fig. 1

INVENTOR fia/ph Higgins i ATToRN l flea 28, 19370 5%. HKGGINS 2,103,365

ARCING GAP Filed July 27, 1935 2 Sheets-Sheet 2 INVENTOR fia/ph HigginsPatented Dec. 28, 1937 PATENT OFFICE ARCING GAP Ralph Higgins, Akron,Ohio, assignor to The Ohio Brass Company, Mansfield, Ohio, a corporationof New Jersey Application July 27,

6 Claims.

This invention relates to arcing gaps for protecting electricalapparatus from excessive voltage and is illustrated as applied to a gapsimilar to that disclosed in Patent No. 2,011,136, granted '5' August13, 1935.

One object of the invention is to provide means for quickly interruptingthe arc across the gap before the current flowing in the arc has time totrip the main circuit breakers.

A further object of the invention is to provide an arcing gap equippedwith arc interrupting mechanism in which the action of the interruptingmeans does not interfere with the operation of the gap for recurrentsurges.

' A further object of the invention is to provide an arcing gap havingmeans connected therewith for automatically interrupting the are aftereach of a series of recurrent operations of the gap. A further object ofthe invention is to provide an arcing gap equipped with arc interruptingmeans adapted for repeated operation, the gap being operative to protectthe connected apparatus even after the interrupting means has beenexhausted by repeated operations.

A further object of the invention is to provide a device of the classnamed which shall be of improved construction and operation.

. Other objects and advantages will appear from the followingdescription.

1 The invention is exemplified by the combination and arrangement ofparts shown in the accompanying drawings and described in the followingspecification, and it is more particularly pointed out in the appendedclaims.

' In the drawings:

Fig. 1 is a diagrammatic view illustrating one embodiment of theinvention.

Figs. 2 and 3 are views similar to Fig. 1 showing other forms of theinvention.

Fig. 4 is an elevation of arcing gap apparatus showing one embodiment ofthe form of the invention illustrated diagrammatically in Fig. 3.

Fig. 5 is an end view looking from the right in Fig. 4.

Fig. 6 is a fragmentary top plan view of the arc extinguishing portionof the apparatus shown in Fig; 4.

The primary function of a control gap, such as that shown in the Austinpatent referred to above,

150 is to relieve the high tension line to which it is connected ofabnormal lightning and switching surges before such surges have doneserious damage. Sometimes, in order to afford adequate protectionagainst insulation breakdown or flash- 55 over of station equipment, itis necessary to set the 1935, Serial No. 33,533

gap quite low. Naturally a low setting of the gap will cause it tofunction quite frequently. With one terminal of the gap solidlygrounded, each operation of the gap requires the power are, whichfollows flashover of the gap, to be interrupted by the operation of oneor more of the main line circuit breakers. The operation of the linecircuit breakers is sometimes very objectionable, especially when largeblocks of power are involved and when interruption of power serviceentails great losses to the customers. Also, on some lines that are notequipped with suitable ground relays or high speed over-load relays, themain circuit breakers will often require some time before they willopen. In such cases the long duration of the power are is apt to doconsiderable damage to the arcing tips and other parts of the gap.

To overcome these difficulties, the present invention provides a highvoltage fuse or some other H quick acting circuit breaker in series withthe control gap to clear the control gap before the main line circuitbreakers have a chance to open and before the arc can do any damage tothe gap parts. If such a fuse or quick operating circuit interrupterwere used alone in series with the control gap, the gap would no longerbe solidly grounded after operation of the interrupter and thus shouldanother surge follow immediately, before the fuse can be renewed, whichhappens quite frequently, the control gap would be inoperative and thedesired protection would not be afforded.

To overcome this diificulty, the present invention provides anarrangement which is shown diagrammatically in simple form in Fig, 1. Inthis figure a control gap 10 is provided with a fuse l I in series withthe control gap and be tween the control gap and ground. A relief gap I2is connected in parallel with the fuse H, the

gap I2 being set just high enough that normal voltage will not cause itto arc over after the fuse ll blows. A condenser I3 is connected inparallel with the fuse II and gap l2. If the gap I2 alone were used inparallel with the fuse il, it is apparent that after the fuse I l blows,there would be two gaps l0 and I2 in series between the line and ground.This arrangement, of course, would require a higher voltage to produce aflashover than is required with the fuse H intact. The purpose of thecondenser I3 is to avoid this change in the arcing voltage of the gapdue to the opening of the fuse II. It has been found in practice that acondenser [3 of proper capacity, in parallel with the gap l2, willsupply sufficient charging current to the gap E to maintain thefiashover voltage of the gap l6 substantially constant, notwithstandingoperation of the fuse II. It is not desirable to have the capacity ofthe condenser l3 too great as too high a capacity in this condensertends to maintain a sputtering arc across the gap If? after the fuse Hhas interrupted the power arc. On most sizes of control gaps for variousratings, it has been found that a capacitance of .0003 microfarad issufficient to maintain a substantially uniform operation of the gaplll'with any practical gap l2 in series with the gap l0 and with thefuse H in place or out. The arrangement shown in Fig. 1 insures.continuous protection of the apparatus connected with the gap i 0,notwithstanding operation of the fuse I i to interrupt the power arefollowing flashover of the gap l0. It will be apparent; however, thatafter one operation of the fuse il there is nothing to interrupt asecond power are in case fiashover occurs a second time before the fusel l hasbeen'replaced. However, the arrangement shown in Fig. 1 wouldoperate satisfactory in' all cases except those where a second surgefollows closely after the first and before the fuse H can be replaced.Even in that case the device affords protection for the apparatus sincethe'second surge will flashover the gap l0 and the series gap 12-, atsubstantially'the same voltage as the original flashover, but in thecase of the second surge, before replacement of the fuse H, reliancewill have to be placed upon the main line circuit breaker to interruptthe power arc.

To further reduce the number of possible interruptions, the arrangementshown in Fig. 2 may be used. In this figure a setof any number 7 offuses I4, i and 16 are arranged for successive connection in parallelwith the gap 12. A number of different repeating fuse arrangements areavailable to the trade at present, most of which are operated by amechanical throw-over switch which automatically operates, when one fuseblows, to connect in an unblown fuse. Such a switch is indicateddiagrammatically at H. With this arrangement of multiple fuses, it isstill desirable to provide the relief gap 12 and condenser 13 to insureprotection of the apparatus after the last of the multiple fuses hasbeen exhausted. It is also desirable to employ the gap l2 and condenserl3 .to insure protection during, the time required for the switch toconnect in the nextfuse after one has blown. The operation of any'switchrequires an appreciable time and it sometimes happensthat a second surgefollows so quickly after the first that theintervening time does notpermit the connection of the next fuse in the set. With the arrangementshown in Fig. 2, including the condenser 13 and the relief gap l2, theapparatus is afforded protection even though the second surge shouldfollow so quickly that no time is provided for operation of the switchIV. In case of such operation if the switch gap is less than the gap l2,the arc-over will occur across the switch gap and through the nextadjacent fuse so that the fuse will. operate to break the power arc eventhough the switch has not yet been closed. If a solid ground connectionwere provided in place of the last fuse Hi, the gap 12 would not be,necessary but the condenser i 3 would still be required to supply"charging current and maintain the calibration of the gap in case asurge that blows a fuse is followed immediately by another before theswitch has connected in the next adjacent fuse, for during the time thes'wit ch'is open it forms a'second gap in series with '1, 2 and 3.

the main gap that would increase the fiashover' voltage except for thepresence of the condenser l3.

Another repeating fuse arrangement is shown in Fig. 3. In thisarrangement no reclosing switch mechanism is required but each fuse hasa series gap somewhat shorter than the auxiliary gap i 2. Withthis-arrangement, it is'readily seen that irrespective of the timeinterval between repeat surges, the next fuse is always ready tofunction. The gap 2| in series with the fuse l8 can be made very shortor may even be omitted or bridged since after the operation of the firstfuse 18, the. fuse gap itself will be sufficient to prevent arcingacross the fuse gap on the normal linevoltage imposed upon the fuse gapsby an arc across the gap I0. It is not absolutely essential to have thegaps 22 and 23 of unequal length. However, it is preferred to have them'somewhat different in length in order to insure that both will notoperate at the same instant, which may be possible on some extreme,heavy lightning strokes. r I

Fig. 4 shows the'arrangement illustrated'diagrammatically in Fig. 3applied to a practical form of arcing gap of the type shown in Austinpatent referred to above. In this figure the numeral 24 designates themounting for the ter minal of the gap connected by any suitable means 25to the line to be protected. The terminals 26 and 27 of the gap areprovided with control members 28 for adjusting the gap to various operating conditions. The mounting 24 is supported by insulators 29carried by a grounded base 30. The terminal 2! is carriedby a suitablehead 3| mounted upon a condenser 32 which also serves to insulate thehead 3| from ground. The, condenser 32 corresponds to the condenser 13shown in Figs. 1, 2 and 3. The lower terminal of the condenser 13 isgrounded through its supporting standard 33 which is provided with anarcing horn 34. V

The head 3! is provided with a plurality of arcing horns 35,36 and 31which cooperate respectively with horns 38, 39 and 40 connected to theterminals of fuse members 4|, 42 and 43. The gaps between the horns 35,36 and 3! and their respective fuse members are of varying lengths, thegap between the centralimembers 36 and 39 being the greatest. The horn34 is in the same vertical plane with the horns 36 and 39 and forms'agap between the horn 36- and ground which is in parallel with thevarious fuse members andrwhich corresponds to the gap l2 inFigs.

and the members 34 and '39 respectively have substantially the sameelectrostatic field conditions so as to insure arcing of the gap 36- -39ahead of the longer gap 36-34 to ground. It will be seen that the fusemembers 4|, 42 and 43 are mounted upon'a hinged head 44 which may beswung backwardly into the position shown in broken lines in Fig. 4 tofacilitate renewal of the fuses without danger to the operator. Agrounding arm 45 is preferably connected to the head 44 in position toengage one of the arcing horns when the head 44 is rotated into itsinoperative position. This grounds the head 3| and its connected partsto insure protection to the operator during renewalof the fuses. beenfound desirable to have the-individual :fuse gaps made 'of rod or barends similar to that of theauxiliary relief gap in order to eliminateany polarity or over-voltage effects which would be The gaps between themember 36 It has "1 liable to cause. dissimilar gaps to operatein animproper sequence. The operating head 44 for the fuse gaps is mounted ona grounded shaft which may be rotated by any suitable mechanism withoutendangering the operator. Since the condenser 32 serves the doublepurpose of condenser and insulating support for the terminal 21, thecost of a gap provided with a condenser is very little greater than asimilar gap with the usual insulation for the terminal 21.

The flashover voltage of the condenser 32 need be only slightly greaterthan the fiashover voltage of the auxiliary gap between the members 34and 35.

I claim:

1. In a surge arrester the combination with an arcing gap, of a circuitinterrupter adapted, when open, to provide an open break in the circuitin which it is connected, said interrupter being electrically connectedbetween one terminal of said gap and ground, and a condenser in parallelwith said circuit interrupter between said terminal and ground forsupplying charging current to said arcing gap when said circuitinterrupter is open, the capacitance of said condenser beinginsufficient to produce efl'ective reduction in the crest of a surgevoltage causing discharge across said gap, but the resistance of thepath through said circuit interrupter being low enough to divert themajor portion of the surge current from said condenser and to provide asubstantially direct ground for said current.

2. In a surge arrcster the combination with an arcing gap, of anoverload circuit interrupter adapted, when open, to provide an openbreak in the circuit in which it is connected, said interrupter beingelectrically connected between one terminal of said gap and ground forinterrupting the power are following operation of said gap, and meansfor enabling said gap to operate at approximately the same voltageirrespective of whether said circuit interrupter is open or closed, saidmeans comprising a condenser in parallel with said circuit interrupterthe capacitance of said condenser being not materially more than .0003microfarad, while the impedance of the path through said circuitinterrupter is comparatively, substantially negligible.

3. The combination with an arcing gap, of a circuit interrupter inseries with said gap between one terminal of said gap and ground, acondenser in parallel with said circuit interrupter, and an auxiliarygap in parallel with said circuit interrupter and said condenser.

4. The combination with an arcing gap, of a circuit interrupter inseries between one terminal of said gap and ground, a condenser inparallel with said circuit interrupter, and an auxiliary gap having alower flashover value than said condenser in parallel with saidcondenser and circuit interrupter.

5. The combination with an arcing gap, of an overload circuitinterrupter in series between one terminal of said gap and ground, acondenser of approximately .0003 microfarad in parallel with saidcircuit interrupter, and an auxiliary gap of a lower fiashover valuethan said condenser in parallel with said condenser and circuitinterrupter.

6. Means for protecting electrical apparatus from over-voltage impulsescomprising an arcing gap having one terminal connected with saidapparatus, said gap being adapted to determine the over-voltage impulseat which discharge will occur, a second gap in series with saidfirstnamed gap, and a condenser in parallel with said second gapproviding capacity between its terminals sufiiciently in excess of thecapacity between the terminals of said first-named gap so that thepredominate portion of an impulse voltage impressed on said gaps inseries will be apportioned to said first-named gap to produce fiashoverat approximately the same voltage as if said condenser were a groundedconductor.

RALPH HIGGINS.

